EP2461065B1 - Hinge device with a strand bundle in a shape memory material - Google Patents

Abstract

The device has a shape memory device comprising bundles (21, 22) of wire strands made of electrically conductive shape memory material e.g. one-way shape memory material. Each bundle comprises two power supply terminals between which the strands are electrically connected in series and are heated by Joule effect such that power supply of the bundle drives bending deformation effort of the bundle from an intensity value of electric current, passing through the strands, corresponding to heating of the strands beyond transformation temperature. An independent claim is also included for a space system comprising an articulation device.

Description

The invention relates to the technical field of connection elements between parts or elements in the general sense, allowing angular displacement between said parts and more particularly aims at the joints of which at least a portion of the motorization energy is supplied by the deformation of a shape memory material, in particular during a change in the temperature of said shape memory material.

Throughout the text, a shape memory material is a material having at least two stable shapes at two different temperatures, at least one of which corresponds to a particular geometric shape. The shape of such a material is modified by solid-solid phase transformation (called austenitic-martensitic compared to steels in particular) when it is subjected to a modification of its environment, especially when heated above - or cooled below - a temperature, called transformation temperature, which marks the beginning of a range of temperatures in which the material is deformed progressively between one form and another.

Thus, such a shape memory material can be of the "one-way" type, that is, it deforms to a stable form only when it is heated beyond its transformation temperature. Such a shape memory material may also be of the "two-way" type, having the same characteristic as a "single-sense" shape memory material but which also deforms to a stable shape when it is cooled down below. of its transformation temperature.

The most known shape memory materials are metal alloys including among others nickel-titanium alloys (Ni-Ti).

Knuckle devices actuated by a drive member of shape memory material are known. Electricity is often the source of energy the easiest of use it is preferred for the heating of the drive members of Joule shape memory material.

However, in the known articulation devices, a physical limit opposes the use of the drive members of shape memory material, especially on board vehicles whose energy resources are limited, and which it is often desired to reduce. mass. Indeed, it is often necessary to give up the use of a drive member of shape memory material because of an electrical source of limited intensity which is not sufficient to heat by Joule effect and thus sufficiently deform the material. with shape memory. Alternatively, providing high power intensities to achieve sufficient heating of the shape memory material requires the use of expensive power transformers, which add mass and volume to the vehicle, and result in loss of power. 'energy.

That is why the drive members of shape memory material have been used until very recently for the benefit of more conventional drive members and less power consumers such as springs for example, including spiral springs, or Carpentier's blades.

The Carpentier blades, also often called Carpentier seals, have the advantage of performing the two functions of a motorized articulation, namely actuating and guiding in rotation. They also provide locking in the deployed position. They have therefore been adopted in articulation device applications for the single deployment of a structure, particularly in the field of deploying solar panels, deployable masts, opening lids, etc., of a satellite ( see for example EP 0 939 727 ).

However, carpentier blades used alone have many disadvantages. In particular, they share with the springs the major disadvantage of releasing the mechanical energy they store uncontrollably. This can lead to mechanical shocks, especially shocks composed of vibrations particularly intense at the end of deployment. These shocks are generally harmful for the system on which the joint is mounted.

Thus, the release of mechanical energy by a compressed spring or a Carpentier blade is brutal and can lead to the deterioration of the movable elements mounted at each end of the joint.

To resist this shock at the end of deployment, such joints and / or end pieces are often oversized, which has the disadvantage of inducing a surplus of mass and / or volume.

Thus, when systems are equipped with motorized joints by springs, Carpentier blades or any other elastic member or in the general sense any organ storing energy that can be released suddenly, they are likely to be damaged during deployment (and / or folding) of this joint. This is even more the case when several elements of the same system are interconnected by several joints of this type in series (for example the different solar panels of a satellite). Indeed in the latter case, the deployment (and / or folding) of the joint is violent and difficult to control, with the risk of collisions between the various elements articulated by these joints.

This is why these types of motorization are sometimes replaced or used in combination with a shape memory material to control their speed of deployment, in particular in the form of blocks of shape memory material (see for example US 7,354,033 ). Using a block of shape memory material provides sufficient mechanical energy provided they heat sufficiently. However, their heating is problematic: large heating resistances required, heating by the Joule effect requiring a high intensity, etc. Due to their disadvantages, these devices are also not compatible with autonomous systems whose resources are to be saved. energy, for example satellites or aircraft.

The invention aims to overcome these drawbacks by proposing a motorized articulation device whose motor member does not abruptly discharge its energy.

The invention also relates to such a motorized articulation device which causes little or no impact at the end of deployment when in motion, and in particular no significant mechanical shock at the end of folding / deployment.

The invention furthermore aims at such a motorized articulation device which is self-locking and which can not therefore be unlocked spontaneously from an extended (and / or folded) position.

The invention also relates to a hinge device whose speed of deployment (and / or folding) is controlled, particularly when it comprises a self-motorized body.

More particularly, the invention is directed to a motorized articulation device of which at least a portion of the mechanical motor energy and / or the braking / damping power comes from the deformation of a shape memory material.

The invention also aims at providing such a hinge device comprising at least one element of shape memory material whose ratio of the mechanical power it provides on the energy required for its heating is better than that of the driving members. shape memory material known articulation devices of the state of the art.

More particularly, the invention aims to provide such a hinge device requiring a relatively low electric current intensity for its operation.

• le dispositif en matériau à mémoire de forme comprend au moins un faisceau de brins de fil en matériau à mémoire de forme électriquement conducteur, latéralement adjacents et latéralement électriquement isolés les uns des autres, chaque brin tendant à se déformer en flexion à partir d'une température, dite température de transformation, vers une forme mémorisée,
• ladite forme mémorisée de chaque brin de chaque faisceau étant choisie de telle sorte qu'une déformation conjointe en flexion de chacun des brins vers ladite forme mémorisée corresponde à une déformation en flexion du faisceau,
• chaque faisceau comprend deux bornes d'alimentation électrique entre lesquelles les brins sont électriquement en série et adaptés pour pouvoir s'échauffer par effet Joule, de sorte que l'alimentation électrique dudit faisceau permet, à partir d'une valeur d'intensité d'un courant électrique parcourant les brins correspondant à leur échauffement au-delà de la température de transformation, d'entraîner un effort de déformation en flexion du faisceau.

To do this, the invention relates to a hinge device connecting two end pieces, adapted to occupy at least one folded position and at least one deployed position, and comprising a device of shape memory material connecting the two parts. end-piece, characterized in that:

• the shape memory material device comprises at least one bundle of wire strands of electrically conductive shape memory material, laterally adjacent and laterally electrically insulated from each other, each strand tending to flex in deformation from a temperature, called transformation temperature, towards a memorized form,
• said memorized form of each strand of each beam being chosen so that a joint bending deformation of each of the strands towards said stored shape corresponds to a bending deformation of the beam,
• each bundle comprises two power supply terminals between which the strands are electrically in series and adapted to be heated by the Joule effect, so that the power supply of said bundle makes it possible, from an intensity value of an electric current flowing through the strands corresponding to their heating beyond the transformation temperature, to cause a deformation force in bending of the beam.

A hinge device according to the invention can be implemented in many applications, and especially for applications requiring a single deployment or folding movement. It is particularly useful in the case of folded structures that it is desired to unfold at a distance, for example the solar panels of a satellite that is sent folded to reduce the volume on board a launcher and that it is desired to be able to deploy in space. It is then a single use deployment of the hinge device.

However, nothing prevents such a device that is reusable several times, for repeated bending and unfolding, with or without locking in the extended position and / or in the folded position; for example with at least one beam of shape memory material of the two-way type, or with at least two beams of shape memory material operating alternately in opposite directions (one bends to a stored shape by forcing flexion of the second, and the second straightened to a memorized form by forcing the straightening of the first).

In addition, a hinge device according to the invention connects two end pieces, that is to say that an end piece can be mounted at each end of the hinge device. The hinge device ensures articulation between these two end pieces movable relative to each other.

End pieces according to the invention or end elements in the general sense may be of any type, for example masts, panels, a cover and a main structure, etc.

A beam according to the invention consists of at least two strands, that is to say two filamentary elements, each connecting the two end pieces of a hinge device according to the invention. In an advantageous embodiment, these strands are made from the same core wire of shape memory material, of constant section, and disposed in an insulating sheath. The strands resulting from such a thread therefore all have the same section. In an advantageous embodiment of the invention, the set of strands of a bundle is in fact a single and single wire folded several times at the ends of the bundle.

The strands of a beam according to the invention advantageously have a core of shape memory material which is electrically conductive, which is the case with most shape memory alloys. In addition, such a shape memory material has a non-zero resistivity sufficient for its heating and Joule effect in the environment in which a device according to the invention is intended to be used. In particular for hinge devices intended to be mounted on a space system, the shape memory material must have a non-zero resistivity at temperatures prevailing in space.

Furthermore, strands according to the invention also advantageously have electrical insulation on their lateral external surface. This insulation can be made in different ways, for example with a varnish, with an insulating sheath, or by casting all the strands of the bundle in an electrically insulating material.

It is therefore possible to choose the section of the strands of a beam according to the resistivity, the available current intensity and the transformation temperature of the shape memory material used. Alternatively, it is also possible to choose a shape memory material as a function of its resistivity and of its transformation temperature in order to satisfy the dimensions of a hinge device according to the invention (number of beams, number of strands per beam , section of each strand etc.).

This lateral insulation is necessary. Indeed, the strands of a beam according to the invention are mechanically contiguous, that is to say they are arranged side by side laterally in mechanical contact with each other. The strands can be made contiguous in different ways, so they can for example be literally glued to each other. According to another embodiment, they can be held within a bundle, for example by clamps, while having a certain freedom to slide longitudinally relative to each other in order to avoid excessive longitudinal tensions. during a significant bending.

Advantageously, the beam is and remains a contiguous bundle whatever the geometric shape that it adopts. This arrangement of the contiguous bundle beam shape memory material makes it possible to multiply the developed mechanical power to an equal volume of shape memory material. This arrangement also makes it possible to maintain a beam that is resistant over time, and in particular to prevent it from tapering after numerous folding and deployment cycles.

Since the strands are laterally joined, the lateral electrical insulation makes it possible to avoid a short circuit when the strands are traversed by an electric current.

Indeed, in the present invention, the strands of the same beam are electrically connected in series so that the current advantageously travels the entire length of a first strand before propagating to a second strand, and so on. Such a beam thus opposes an electrical resistance of substantial value at the passage of the current which is at least equal to the sum of the individual electrical resistances of each of the strands which constitute it.

A beam according to the invention therefore consists of strands electrically connected in series with each other and mechanically in parallel with each other. In this way, each strand can provide an elementary work which contributes to the total work of the beam, said total work corresponding in fact to the sum of the elementary work of the strands of the beam.

It is therefore possible to choose the section of the strands of a beam according to the resistivity and the transformation temperature of the shape memory material used. Alternatively, it is also possible to choose a shape memory material as a function of its resistivity and of its transformation temperature in order to satisfy the dimensions of a hinge device according to the invention (number of beams, number of strands per beam , section of each strand etc.).

This arrangement of contiguous strands connected in series within a bundle has many advantages.

Thus, the electric current required to heat the strands by Joule effect is much lower than the electric current required for heating by Joule effect of a volume of "bulk" shape memory material. This characteristic is an important advantage in the case where the articulation device is embedded in autonomous systems whose energy resources are to be saved or which are not adapted to provide currents of high intensity, for example onboard aircraft. vehicles, space systems such as satellites, or aircraft.

In addition, all the strands deform together, that is to say simultaneously (being heated by the same electric current) and to the same shape, so that they tend towards the same stored form which corresponds to the stored form of the beam they constitute.

The strands of the same beam exert simultaneous individual mechanical forces in parallel, the total mechanical stress of a beam being a sum of the individual forces of each strand.

The ratio of the mechanical energy developed on the electrical intensity supplied is therefore very much improved.

Each beam advantageously has more than two strands.

Also, several beams in the electrical sense can be nested within the same elongated structure (the same mechanical actuator). That is to say that two independent series of strands connected in series are electrically in parallel in the same elongate structure connecting two end pieces. In the present invention a beam is a beam in the electrical sense of the term: a series of wires connected in series electrically. Several beams can be mechanically grouped into one and the same actuator.

A beam according to the invention thus has an electrical connection at each of its electrical ends (first end of the first strand and second end of the terminal strand) adapted to connect each set of strands in series to an external power supply not described herein. invention.

Each of the beams can be electrically connected independently to a power supply. Alternatively, at least two, more, or all of the beams can be electrically connected to each other in series.

• maintenir un dispositif d'articulation dans une première position pliée ou déployée, notamment dans une position pliée,
• motoriser le dispositif d'articulation en pliage et/ou en déploiement de façon contrôlée,
• amortir des chocs avant, pendant et après le déploiement (et/ou le pliage) du dispositif d'articulation,
• verrouiller le dispositif d'articulation dans une deuxième position (respectivement déployée ou pliée), notamment dans une position déployée.

A beam according to the invention is particularly suitable for:

• maintaining a hinge device in a first folded or deployed position, in particular in a folded position,
• motorize the articulating device in folding and / or deployment in a controlled manner,
• damping shocks before, during and after deployment (and / or folding) of the articulation device,
• locking the hinge device in a second position (respectively deployed or folded), in particular in an extended position.

Advantageously and according to the invention, the shape memory material is of the one-way type, remaining in its memorized form even after cooling below its transformation temperature.

With a shape memory material of the single-direction type, it is possible to produce even-numbered beams in opposition of operation allowing successive phases of folding and deployment. For this we feed a first group (half the total number) of beams for folding of the hinge device, said beams tending to a bent stored shape deform the other beams at the same time as they bend the joint. Then, the first group of beams being no longer fed (or even cooled), the second group is fed to a stored expanded form and deforms the first group of beams at the same time that it deploys the joint.

However, it is often sought to achieve single-use articulation devices, that is to say that serve only a single folding movement or a single deployment movement. This is the case for example for articulation devices for launching a satellite with its solar panels folded to reduce the volume at launch and deploy a single time when the satellite is in space.

Thus, in the case of a one-way articulation device, all the beams are deformed from a folded (respectively extended) biased shape to an expanded stored form (respectively folded) under the effect of heating. , in particular heating beyond their transformation temperature.

In addition, advantageously and according to the invention, said hinge device comprises an articulation joint mechanically connecting the two end pieces, and adapted to occupy at least one folded position and at least one deployed position.

A hinge device according to the invention may comprise such a hinge joint, without this being necessary. Indeed, a hinge joint according to the invention has the function of ensuring a mechanical connection articulated between two end pieces. Also, a hinge device comprising no hinge joint is provided by the invention. In all embodiments, the shape memory device device, including the beams, also provide this function of articulation between the two end pieces.

A hinge joint according to the invention may be of any type since it provides a hinge in flexion and / or rotation between at least one folded position and at least one deployed position. It is advantageously produced by a connection of elastic material in flexion, that is to say intrinsically possessing elastic properties or in the form of thin enough elements for the material to be made elastic in flexion. It can in particular be self-propelled, that is to say, store energy prior to its deployment (or folding) that it frees to perform a deployment (respectively a folding) autonomously.

However, nothing prevents such a hinge joint does not include elastic material. It can thus, for example, consist of mechanical elements forming a mechanical connection in bending and / or rotation, for example a hinge, a ball joint, a plain bearing, a rolling bearing, etc.

In addition, in a device according to the invention a hinge joint connects two end pieces, that is to say that an end piece is mounted at each end of the hinge joint. The hinge joint ensures articulation between these two end pieces movable relative to each other.

Advantageously, each of the longitudinal ends of a bundle according to the invention is attached respectively to one of the two end pieces and / or to one of the two ends of the hinge joint. Thus, the beam is able to drive the hinge joint between a folded position and an extended position and / or between an extended position and a folded position.

• maintenir un joint d'articulation dans une première position pliée ou déployée, notamment dans une position pliée, que le joint soit automoteur ou non,
• accompagner le joint d'articulation, c'est-à-dire assurer des fonctions de :
  • o motorisation si le joint d'articulation est passif ou bloqué,
  • o contrôle de la vitesse de déploiement (et/ou de pliage) du joint d'articulation si ce dernier est automoteur, par exemple dans le cas où le joint d'articulation comporte une pièce élastique (ressort, joint de Carpentier, etc.),
  • o amortissement des chocs avant, pendant et après le déploiement (et/ou le pliage) du joint d'articulation,
• verrouiller le joint d'articulation dans une deuxième position (respectivement déployée ou pliée), notamment dans une position déployée.

A beam according to the invention is particularly suitable for:

• maintaining a hinge joint in a first folded or extended position, especially in a folded position, whether the seal is self-propelled or not,
• accompany the articulation joint, that is to say perform functions of:
  • o motorization if the articulation joint is passive or blocked,
  • o control of the deployment speed (and / or folding) of the articulation joint if the latter is self-propelled, for example in the case where the hinge joint comprises an elastic piece (spring, Carpentier seal, etc.). ,
  • o shock absorption before, during and after the deployment (and / or folding) of the joint,
• locking the hinge joint in a second position (respectively extended or folded), in particular in an extended position.

Indeed, by heating a beam of shape memory material according to the invention above its transformation temperature, it tends to deform in bending to a stored shape corresponding to a temperature range beyond the range of temperatures at which they deform from one form to another, and whatever the hinge joint associated with it in a device according to the invention.

In addition, advantageously and according to the invention, said hinge joint is a self-propelled joint from a folded and self-locking position in the deployed position, comprising at least one strip, called curved strip, having a transverse cross-section of monotonous concave curvature in the deployed position, each curved strip being adapted to be bent elastically in flexion with elastic bending stresses able to actuate at least partially the deployment of said articulation device.

A strip is a portion of material whose thickness is much smaller than the rest of its dimensions. An example of a curved strip as described above is a seal (or blade) Carpentier.

A curved strip according to the invention is a section with concave section seen from one side, and convex from the opposite side. It has an axis longitudinal axis corresponding to its principal direction, along its largest dimension (length), in the deployed position. A section through a plane orthogonal to this longitudinal axis, that is to say a transverse cross section, of such a curved strip has a curve of curvature which is always of the same sign, free of point of inflection.

A curved strip according to the invention is folded into an initial position in which it stores mechanical energy in elastic form. It releases this energy by unfolding, so that its elastic potential energy in the deployed position is lower than its elastic potential energy in the folded position. Thus, it has a stable position in the deployed position and an unstable position in the folded position.

In addition, the curvature of the curved strips in the deployed state forms a folding effect which produces a very high buckling strength of the hinge device in the deployed position and therefore a locking of the hinge in the deployed position.

However, it happens that a curved strip, including Carpentier's type of seal, hangs during deployment and / or unlocks its deployed position under the effect of external shocks. One or more beams (x) according to the invention thus has the advantage of providing a driving force to pass any blocking points during deployment of a hinge joint comprising such a device (s). ) curved band (s). This (s) beam (s) also provides locking in the deployed position. Indeed, the shape memory material has a stable shape, said shape stored in the deployed position. In particular, a single-way shape memory material having joined its stored form is in a stable form regardless of the temperature at which it is located.

Advantageously and according to the invention, in one embodiment said hinge joint comprises three curved strips, two of which, located laterally on either side of the third, have a concavity oriented in the same meaning, of direction contrary to the orientation of the concavity of the third curved band.

The orientation of a concavity can for example be represented by the sum vector of the vectors representing the acceleration of an object traveling at a constant linear velocity the cross section of a curved strip on the concave side of the strip, or for example by the sum vector of the unit normal vectors at each point of the concave surface.

In this embodiment, the concavity of two of the three curved strips is oriented in the same direction, that is to say that the position of the second curved strip is obtained by a simple translation of the position of the first curved band. The concavity of the third curved strip is oriented in the same direction in the opposite direction, that is to say that the position of the third curved strip is obtained by a rotation of one of the first two curved strips of 180 ° around its longitudinal axis and a translation.

In addition the first two bands are located laterally on either side of the third central band (the orientations of their concavity are not collinear but parallel). This structure not only makes it possible to fold the three curved strips orthogonal to their longitudinal axis to store an elastic energy, but it also allows a guide of the joint so that it unfolds in a single fixed direction avoiding any parasitic rotation around it. a longitudinal axis of the hinge device during its deployment.

In addition, the three curved bands may or may not be placed in the same plane. Advantageously at least the two curved strips whose concavity is oriented in the same direction are placed in the same plane.

Many other ways of arranging one or more curved strip (s) to make a hinge joint according to the invention can be envisaged. For example, the three curved bands can be distributed concentrically around the same axis, their concavity being oriented towards this axis, of so that they form an ellipsoidal theoretical envelope - in particular cylindrical of revolution - around this axis.

Moreover, several strips can be formed from the same wall of suitable corrugated form in which openings are made separating curved strips formed by the remaining wall strips.

Advantageously and according to the invention, in another embodiment, said hinge joint comprises a tubular wall having at least two longitudinal openings separating at least two longitudinal curved strips.

The tubular wall has a tube shape in the fully deployed position. This tube may have different profiles in cross-section, including an ellipsoidal profile, in particular a circular profile.

The tubular wall makes it possible to produce the curved strips in the same material of the same thickness, and to form curved strips easily by forming longitudinal openings on said tubular wall. The openings in the wall are therefore of complementary shape of the curved strips. Such openings extend longitudinally along the main axis of the tube formed by the tubular wall in the deployed position.

The number of longitudinal openings in the wall determine the number of curved strips formed: there are as many curved strips as there are longitudinal openings. At least two openings are made in said tubular wall, that is to say that it comprises at least two curved strips.

In particular, advantageously and according to the invention, said tubular wall has three lateral openings distributed uniformly over its diameter and separating three longitudinal curved strips.

When such a hinge joint is in the folded position, two of the three curved strips of the tubular wall are advantageously folded in one direction and the third is folded in the other direction.

In addition, a hinge device according to the invention has two beams mounted outside and on each side of the space included within the theoretical envelope of said tubular wall.

A hinge joint in the form of a tubular wall separates the space in two, between a space, said interior space, confined by the theoretical envelope of the tubular wall, and the rest of the space, said external space . So that two bundles of strands according to the invention are on the outside of the hinge joints.

Advantageously, the two beams are arranged on either side of the hinge joint. They thus define, in the deployed position, a plane containing the main axes of each of the two beams in the deployed position.

A hinge device according to the invention is advantageously folded on one side or the other of this plane, so as to fold the two beams in a similar curvature, without causing extension and / or exaggerated retraction of the one or the other. In particular, the two beams are not mounted in such a way that in the folded position a first beam has a radius of curvature greater than the radius of curvature of the hinge joint and a second beam has a radius of curvature smaller than the radius of curvature. joint joint.

This arrangement is also advantageous for a hinge device according to the invention having more than two beams.

In general, the beams are advantageously mounted around said hinge joint so as not to interfere with the folding of the curved strips.

Alternatively, each bundle of a hinge device according to the invention comprises from 2 to 10,000 strands connected in series electrically, in particular between 10 and 500 strands connected in series electrically.

Such a bundle extends longitudinally along a curved strip, and is advantageously and predominantly located in the space between said curved strip and a plane containing at least one of the strings of said curved strip. In particular, a beam is mainly included in the delimited space by said curved strip and a plane containing two of its largest ropes, said ropes being distinct. Such a beam is "in" the concavity formed by a curved band.

This arrangement makes it possible to produce a hinge device according to the invention that is more compact than when the beams are arranged outside the hinge joint. The beam located in the concavity of a curved strip may be in contact with the latter.

In addition, the number of curved strips having a beam housed in its concavity can vary. For example, two out of three symmetrical curved strips may have a beam according to the invention in their concavity. Similarly, the same curved strip may have several beams housed in its concavity.

Thus, advantageously, a hinge device according to the invention comprises two beams each arranged between a curved strip and a plane comprising a cord of said curved strip.

A beam of one of the devices according to the invention has characteristics chosen according to the various embodiments and / or applications of the hinge device according to the invention. Indeed, the technical characteristics of a beam can be chosen for example as a function of: the number of beams on the articulation device, the nature of the articulation joint (in particular self-propelled or not), the dimensions of the articulation device , the power of effort to be developed by each of the beams, the type of effort to be developed by a beam (motorization or braking for example), external conditions of deployment (respectively folding) (eg in a fluid, in space, at a certain temperature, ...), etc.

In particular in a bundle according to the invention, it is possible for example to choose: the shape memory material, the length of the bundle, the number of strands, the cross-section of shape-memory material of each strand, the insulating material between the strands, etc.

The shape-memory material can be chosen according to its resistivity, and the number and length of the strands of a bundle, particularly the section depending on the mechanical torque which one wishes to obtain the number of bundles, can be adapted. effective of each strand.

Advantageously and according to the invention, each bundle comprises from 2 to 10,000 strands connected in series electrically.

A larger number of strands can increase the electrical resistance, and thus to obtain a larger heating electric current of equal intensity. In addition, a very large number of strands makes it possible to develop a greater effort each strand contributing to the total effort developed by the beam to which it belongs.

In particular, advantageously and according to the invention, each bundle comprises from 10 to 500 strands connected in series electrically.

In addition, a hinge device according to the invention is advantageously adapted to be mounted on a satellite, each hinge joint and each beam being in a folded position at launch, and intended to be deployed in microgravity space .

Indeed, the invention proposes a hinge device of small dimensions, low weight, simple and reliable, providing a single deployment and locking in the deployed position, damping possible shocks or vibrations before, during and after deployment, whose speed of deployment is controlled, and consuming only little electrical energy, in particular requiring only a low electrical intensity compared to the mechanical power developed.

The invention also relates to a hinge device characterized in combination by all or some of the characteristics mentioned above or below.

The invention also extends to any space system equipped with at least one hinge device characterized in combination with all or part of the characteristics mentioned above or below. In particular the invention extends to any space system equipped with such a hinge device to be able to present at least one element, for example a photovoltaic panel (s), in the folded position at launch, intended to be deployed (s) ) and locked in microgravity in space.

• la figure 1a est une vue schématique d'un dispositif d'articulation selon un premier mode de réalisation conforme à l'invention comportant une paroi tubulaire présentant trois ouvertures, dans une position pliée,
• la figure 1b est une vue schématique d'un dispositif d'articulation selon l'invention, conforme à la figure 1a, dans une position déployée,
• la figure 1c est une vue schématique d'un dispositif d'articulation selon l'invention, en coupe transversale selon le plan I-I de la figure 1b,
• la figure 2a est une vue schématique d'un dispositif d'articulation selon un deuxième mode de réalisation conforme à l'invention comportant trois bandes courbes, dans une position pliée,
• la figure 2b est une vue schématique d'un dispositif d'articulation, conforme à la figure 2a, dans une position déployée,
• la figure 2c est une vue schématique d'un dispositif d'articulation, en coupe transversale selon le plan II-II de la figure 2b,
• la figure 3a est une vue schématique d'un dispositif d'articulation selon un troisième mode de réalisation conforme à l'invention comportant deux pièces d'extrémité réalisant un joint d'articulation de type liaison pivot de par leur complémentaires, dans une position pliée,
• la figure 3b est une vue schématique d'un dispositif d'articulation selon l'invention, conforme à la figure 3a, dans une position déployée.

Other aims, features and advantages of the invention appear on reading the following description of two preferred embodiments given by way of non-limiting examples, and which refer to the appended figures in which:

• the figure 1a is a schematic view of a hinge device according to a first embodiment according to the invention comprising a tubular wall having three openings, in a folded position,
• the figure 1b is a schematic view of a hinge device according to the invention, in accordance with the figure 1a , in an unfolded position,
• the figure 1c is a schematic view of a hinge device according to the invention, in cross section along the plane II of the figure 1b ,
• the figure 2a is a schematic view of a hinge device according to a second embodiment according to the invention comprising three curved strips, in a folded position,
• the figure 2b is a schematic view of a hinge device, in accordance with the figure 2a , in an unfolded position,
• the Figure 2c is a schematic view of a hinge device, in cross section along the plane II-II of the figure 2b ,
• the figure 3a is a schematic view of a hinge device according to a third embodiment according to the invention comprising two end pieces making a pivot joint type joint joint by their complementary, in a folded position,
• the figure 3b is a schematic view of a hinge device according to the invention, in accordance with the figure 3a , in an unfolded position.

A hinge device according to a first embodiment shown on the Figures 1a, 1b and 1c has a hinge joint in the form of a tubular wall connecting two end pieces 31, 32, cylindrical and each mounted in a longitudinal end of the hinge joint.

The hinge device has a main longitudinal direction in the extended position ( figure 1b ). The tubular joint has a cylindrical theoretical envelope of revolution about an axis, said longitudinal axis.

The hinge joint has three openings forming three strips 11, 12, 13 constant monotonous curvature curves whose concave face is oriented towards the longitudinal axis. The openings of the tubular wall are of oblong shape, oriented in the longitudinal direction and parallel to each other. These openings are also of identical shape and uniformly distributed around the perimeter of the tubular wall, that is to say that they are at 120 ° to each other with respect to the longitudinal axis. So that the three strips 11, 12, 13 curves are identical and they also uniformly distributed around the perimeter of the tubular wall, at 120 ° from each other with respect to the longitudinal axis.

In the folded position shown on the figure 1a two strips 11, 12 curves are folded on themselves on their inner face, that is to say that their concave faces (facing the longitudinal axis in the deployed position) are found opposite each other; in folded position. The third curved band 13 is folded back on itself on its external face, that is to say that its convex face (located on the outer side of the tubular wall in the deployed position) is found in opposite position folded. Nothing prevents folding such a joint in another direction, especially in the opposite direction.

In this embodiment two identical bundles 21, 22 are arranged outside the hinge joint, on either side of the latter. They are therefore symmetrical by a rotation of 180 ° with respect to the longitudinal axis.

Each bundle 21, 22 consists of a single wire whose core is an electrically conductive shape memory material and having an electrically insulating sheath. In each bundle 21, 22, said wire is folded several times on itself at the ends of the bundle, so that it forms a bundle consisting of several identical strands connected in series and laterally electrically insulated from each other. The number of these strands may vary for example between 10 and 10,000, in particular be of the order of 20.

The strands constituting each of the bundles 21, 22 are glued to each other so that they mechanically form a beam in one piece. A single set of strands electrically in series constitutes each bundle.

Each of the bundles 21, 22 is mechanically fixed to each of the tips of the hinge joint by fixing points 41, 42, 43, 44 near the ends of the longitudinal bundles so that the bundles can accompany the seal. articulation in its deployment movement.

Indeed, the shape memory material used to produce the beams 21, 22 is a single-sided shape memory material whose unique stored shape corresponds to an extended position represented on the figure 1b . It is therefore previously deformed under stress in its folded form shown in FIG. figure 1a then it is actuated by an electric current supplied by an external power supply not shown in the figures, which allows it to heat up by the Joule effect to its transformation temperature beyond which it exerts a bending force tending to deploy the hinge device from a position shown on the figure 1a towards an extended position represented on the figure 1b .

For example, it is possible to use a shape memory alloy in the family of nickel-titanium alloys with resistivity of between 0.5 × 10 ^-6 Ω.m and 1.1 × 10 ^-6 Ω · m (respectively in austenitic and martensitic phase). and whose transformation temperature range is between 70 and 90 degrees Celsius. Consequently, it is possible to provide a 20-strand bundle of 0.63 mm section Ni-Ti alloy for Joule heating by a current of 1 amperes intensity. Such device makes it possible to obtain a torque of between 0.1 and 30 Nm, in particular of the order of magnitude of 1 Nm

In this particular embodiment, the shape memory alloy material changes from ambient temperature to a temperature of about 100 ° C in a few minutes (about 2 minutes). Thus a complete deformation of a first form to a shape stored in a time generally between 1 minute and 90 min, in particular in about 2 to 10 minutes.

Each bundle 21, 22 and therefore each strand of this bundle has been deformed under stress in the same folded form. The position of the beams with respect to the hinge joint therefore determines in which direction the joint can be folded, or on one side or the other of the plane containing each of the two beams 21, 22 in the deployed position. Indeed, in the case where the number of curved strips on a tubular wall type joint is odd, as in the example shown in FIGS. Figures 1a, 1b and 1c there is a strong asymmetry between the two directions in which the joint can be bent.

Moreover, each bundle and therefore each strand of this bundle has the same substantially rectilinear stored shape as shown in FIG. figure 1b .

A hinge device according to a second embodiment shown on the Figures 2a, 2b and 2c has a hinge joint consisting of three strips 11, 12, 13 curves connecting two end pieces 31, 32 to which they are attached.

The hinge device has a main longitudinal direction in the extended position ( figure 2b ) and a symmetry with respect to this longitudinal axis.

Two strips 11, 12 outer curves of the hinge joint are substantially in the same first plane P1 and they are symmetrical with respect to a second plane P2 orthogonal to the foreground and containing the longitudinal axis. A third central curved strip 13 has a longitudinal axis of symmetry parallel to the longitudinal axis 5 contained by this second plane P2. The central curved strip 13 can be obtained by a rotation of 180 ° and a translation of any one of the two strips 11, 12 external curves, so that its concavity is oriented in the same direction but in a direction opposite to the concavities of the two bands 11, 12 external curves. The three curved bands are geometrically identical.

The central curved strip 13 is substantially in a plane P2 parallel to the first plane P1 in which are the two strips 11, 12 external curves.

This arrangement of the strips 11, 12, 13 curves makes it possible to create an asymmetry of the hinge joint which is therefore only allowed to bend in two directions, on one side or the other of the plane P1 (or P2) .

In the folded position shown on the figure 2a , the two strips 11, 12 external curves are folded back on themselves on their inner face, that is to say that their concave face is found vis-à-vis in the folded position. The central curved strip 13 is folded on itself on its outer face, that is to say that its convex face is found in facing position in the folded position. In the folded position, the central curved strip 13 protrudes between the two strips 11, 12 external curves. There is therefore a sufficient lateral distance between each strip 11, 12 external curves and the central curved strip 13. Nothing prevents folding such a joint in the opposite direction.

In this embodiment two identical bundles 21, 22 are disposed inside the hinge joint. They are each housed longitudinally in the concavity of one of the bands 11, 12 external curves. They are therefore symmetrical with respect to the plane P2.

Each bundle 21, 22 consists of a single wire whose core is an electrically conductive shape memory material and having an electrically insulating sheath. In each bundle 21, 22, said wire is folded several times on itself at the ends of the bundle, so that it forms a bundle consisting of several identical strands connected in series and laterally electrically insulated. each other. The number of these strands may vary for example between 10 and 10,000, in particular be of the order of 20.

The strands each constituting beams 21, 22 are glued together so that they form a monobloc beam mechanically.

Each of the bundles is mechanically fixed to each of the end pieces 31, 32 by fixing brackets 45, 46 so that they can accompany the hinge joint in its deployment movement.

Indeed, the shape memory material used to produce the beams 21, 22 is a single-sided shape memory material whose unique stored shape corresponds to an extended position represented on the figure 2b . It is therefore previously deformed under stress in its folded form shown in FIG. figure 2a then it is actuated by an electric current supplied by an external power supply not shown in the figures, which allows it to heat up by the Joule effect to its transformation temperature beyond which it exerts a bending force tending to deploy the hinge device from a position shown on the figure 2a towards an extended position represented on the figure 2b .

For example, a shape-memory alloy can be used in the family of nickel-titanium alloys with resistivity of between 0.5 × 10 ^-6 Ω.m and 1.1 × 10 ^-6 Ω · m (respectively in austenitic and martensitic phase). and whose transformation temperature range is between 70 and 90 degrees Celsius. Consequently, it is possible to provide a 20-strand bundle of 0.63 mm section Ni-Ti alloy for Joule heating by a current of 1 amperes intensity. Such a device makes it possible to obtain a torque of between 0.1 and 30 Nm, in particular of the order of magnitude of 1 Nm.

In this particular embodiment, the shape memory alloy material changes from ambient temperature to a temperature of about 100 ° C in a few minutes (about 2 minutes). Thus a complete deformation of a first form to a shape stored in a time generally between 1 minute and 90 min, in particular in about 2 to 10 minutes.

Each bundle 21, 22 and therefore each strand of this bundle has been deformed under stress in the same folded form.

Moreover, each bundle and therefore each strand of this bundle has the same substantially rectilinear stored shape as shown in FIG. figure 2b .

A hinge device according to a third embodiment shown on the Figures 3a and 3b has a hinge joint in the form of two hinge parts 14, 15 forming a hinge joint. This hinge joint makes a pivot connection about a hinge axis 6.

In addition, the two parts 14, 15 of articulation are respectively connected to two parts 31, 32 end movable relative to each other.

The hinge device has a main longitudinal direction in the extended position ( figure 3b ).

In this embodiment, the hinge joint consisting of hinge parts 14, 15 is not self-propelled. The beams 21, 22 of shape memory material are therefore the only driving members for the deployment of the articulation device of a folded position ( figure 3a ) at an extended position ( figure 3b ).

The beams 21, 22 also provide a locking function of the hinge joint in the deployed position.

In this embodiment two identical bundles 21, 22 are arranged outside the hinge joint, on either side of the latter. They are therefore symmetrical with respect to a plane containing the longitudinal axis.

Each bundle 21, 22 consists of a single wire whose core is an electrically conductive shape memory material and having an electrically insulating sheath. In each bundle 21, 22, said wire is folded several times on itself at the ends of the bundle, so that it forms a bundle consisting of several identical strands connected in series and laterally electrically insulated. each other. The number of these strands may vary for example between 10 and 10,000, in particular be of the order of 20.

The strands constituting each of the bundles 21, 22 are glued to each other so that they mechanically form a beam in one piece. A single set of strands electrically in series constitutes each bundle.

Each of the bundles 21, 22 is mechanically fixed to each of the hinge joint parts 14, 15 by two fixing points 41, 42 close to the longitudinal ends of the bundles, so that said bundles can accompany the joint joint in its deployment movement.

Indeed, the shape memory material used to produce the beams 21, 22 is a single-sided shape memory material whose unique stored shape corresponds to an extended position represented on the figure 3b . It is therefore previously deformed under stress in its folded form shown in FIG. figure 3a then it is actuated by an electric current supplied by an external power supply not shown in the figures, which allows it to heat up by the Joule effect to its transformation temperature beyond which it exerts a bending force tending to deploy the hinge device from a position shown on the figure 3a towards an extended position represented on the figure 3b .

For example, a shape-memory alloy can be used in the family of nickel-titanium alloys with resistivity of between 0.5 × 10 ^-6 Ω.m and 1.1 × 10 ^-6 Ω · m (respectively in austenitic and martensitic phase). and whose transformation temperature range is between 70 and 90 degrees Celsius. Consequently, it is possible to provide a 20-strand bundle of 0.63 mm section Ni-Ti alloy for Joule heating by a current of 1 amperes intensity. Such a device makes it possible to obtain a torque of between 0.1 and 30 Nm, in particular of the order of magnitude of 1 Nm.

In this particular embodiment, the shape memory alloy material changes from an ambient temperature to a temperature of about 100 ° C in a few minutes (about 2 minutes). Thus a complete deformation of a first form to a shape stored in a time generally between 1 minute and 90 min, in particular in about 2 to 10 minutes.

Each bundle 21, 22 and therefore each strand of this bundle has been deformed under stress in the same folded form.

Moreover, each beam and therefore each strand of this beam has substantially the same stored form as represented on the figure 3b .

The invention may be subject to numerous variants with respect to the embodiments described above and shown in the figures.

In particular, it may not include a hinge joint, the articulation between two end pieces being then made only by beams of shape memory material.

In addition, when it comprises at least one hinge joint, it applies to all types and all forms of hinge joint. Thus, nothing prevents the use of hinge joint implementing other hinge elements that curved strips (Carpentier joints), or a different number and / or a different distribution of curved strips.

In particular, nothing prevents the use of a hinge joint that is not self-locked in the deployed position (or in the folded position), associated for example with two-way type shape memory materials, to produce a device articulation able to bend and deploy several times.

In addition it is possible to choose between different known shape memory materials according to their own characteristics to achieve the bundles of strands.

A hinge device according to the invention may also comprise a different number of beams and other distributions of the latter. The number of strands, their length, their section, their shape memory material, their insulation, etc., of each bundle must be adapted to each application of a hinge device according to the invention.

Also, nothing prevents a beam of shape memory material has a different length in the folded position in the deployed position, particularly in the case of a shape memory material which retracts or extends between one and the other positions.

Claims (12)

1. Articulation device connecting two end pieces (31, 32), said device being suitable to be able to occupy at least one folded position and at least one deployed position, and including a device made of shape-memory material connecting the two end pieces, characterised in that:

   - the device made of shape-memory material comprises at least one bundle (21, 22) of strands of wire made of electrically conductive shape-memory material, said strands being laterally adjacent to one another and laterally electrically insulated from one another, each strand tending to be flexurally deformed to a memorised shape starting from a certain temperature, called the transformation temperature,

   - said memorised shape of each strand of each bundle (21, 22) being selected so that a linked flexural deformation of each of the strands to said memorised shape corresponds to a flexural deformation of the bundle (21, 22),

   - each bundle (21, 22) includes two electrical supply terminals, between which the strands are electrically in series and suitable to be able to be heated up by Joule effect, so that the electrical supply of said bundle (21, 22) enables a flexural deformation load on the bundle (21, 22) to be brought about, starting from an intensity value of an electric current flowing through the strands corresponding to their heating to beyond the transformation temperature.
2. Articulation device according to Claim 1, characterised in that the shape-memory material is of the one-way type, remaining in its memorised shape even after cooling to below its transformation temperature.
3. Articulation device according to one of Claims 1 or 2, characterised in that said device further includes an articulated joint mechanically connecting the two end pieces (31, 32) and suitable to be able to occupy at least one folded position and at least one deployed position.
4. Articulation device according to Claim 3, characterised in that said articulated joint is a self-propelling joint starting from a folded position and a self-locking joint in the deployed position, including at least one strip, called a curved strip (11, 12, 13), having a curved cross section of monotonic concave curvature in the deployed position, each curved strip (11, 12, 13) being suitable to be flexurally folded elastically with elastic flexural stresses capable of actuating, at least partially, the deployment of said articulation device.
5. Articulation device according to Claim 4, characterised in that said articulated joint includes three curved strips (11, 12, 13), two of which, situated laterally on either side of the third, have a concavity oriented in the same direction, in a direction opposite to the orientation of the concavity of the third curved strip (13).
6. Articulation device according to one of Claims 4 or 5, characterised in that said articulated joint includes a tubular wall having at least two lateral openings separating at least two longitudinal curved strips.
7. Articulation device according to Claim 6, characterised in that said tubular wall has three lateral openings uniformly distributed over its diameter and separating three longitudinal curved strips (11, 12, 13).
8. Articulation device according to one of Claims 6 or 7, characterised in that said device exhibits two bundles (21, 22) mounted on the outside and on each side of the space contained within the theoretical envelope of said tubular wall.
9. Articulation device according to one of Claims 4 to 8, characterised in that said device includes at least one bundle (21, 22) arranged between a curved strip (11, 12, 13) and a plane including a chord of said curved strip.
10. Articulation device according to Claim 9, characterised in that said device includes two bundles (21, 22) each arranged between a curved strip (11, 12, 13) and a plane including a chord of said curved strip.
11. Articulation device according to one of Claims 1 to 10, characterised in that each bundle (21, 22) comprises from 2 to 10,000 strands electrically connected in series, in particular from 10 to 500 strands electrically connected in series.
12. Space system, characterised in that said system includes at least one articulation device according to one of Claims 1 to 11, in order to be able to exhibit at least one element in the folded position at launch, each element being intended to pass into the locked deployed position in space.

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